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Bibliographic Details
Main Authors: Szwagier, Tom, Pennec, Xavier
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2502.06022
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author Szwagier, Tom
Pennec, Xavier
author_facet Szwagier, Tom
Pennec, Xavier
contents Many machine learning methods look for low-dimensional representations of the data. The underlying subspace can be estimated by first choosing a dimension $q$ and then optimizing a certain objective function over the space of $q$-dimensional subspaces (the Grassmannian). Trying different $q$ yields in general non-nested subspaces, which raises an important issue of consistency between the data representations. In this paper, we propose a simple and easily implementable principle to enforce nestedness in subspace learning methods. It consists in lifting Grassmannian optimization criteria to flag manifolds (the space of nested subspaces of increasing dimension) via nested projectors. We apply the flag trick to several classical machine learning methods and show that it successfully addresses the nestedness issue.
format Preprint
id arxiv_https___arxiv_org_abs_2502_06022
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Nested subspace learning with flags
Szwagier, Tom
Pennec, Xavier
Machine Learning
Many machine learning methods look for low-dimensional representations of the data. The underlying subspace can be estimated by first choosing a dimension $q$ and then optimizing a certain objective function over the space of $q$-dimensional subspaces (the Grassmannian). Trying different $q$ yields in general non-nested subspaces, which raises an important issue of consistency between the data representations. In this paper, we propose a simple and easily implementable principle to enforce nestedness in subspace learning methods. It consists in lifting Grassmannian optimization criteria to flag manifolds (the space of nested subspaces of increasing dimension) via nested projectors. We apply the flag trick to several classical machine learning methods and show that it successfully addresses the nestedness issue.
title Nested subspace learning with flags
topic Machine Learning
url https://arxiv.org/abs/2502.06022